Comment by tomatotomato37

7 days ago

I'm curious what the thermal management system on this looks like. On one hand, vacuum being in essence a perfect insulator works in favor of keeping the silicon hot for the very long time it takes to pull a boule while requiring very little energy. On the other hand, you have to make sure the control electronics don't also heat up to 1000C. I'm also curious how you keep the molten silion separate from the crystal without gravity keeping it in the crucible. I bet a lot of interesting engineering going on here.

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tomatotomato37

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marcosdumay  4 days ago

Vacuum is only a nearly perfect insulator until a few hundred °C. After that, radiation dominates over every other form of heat exchange, and it stops making any difference.

A couple of meters long steel rod with a dissipator on the end can easily keep electronics at Earth surface temperatures even if you heat the other end to 1000°C.

  • pixl97  4 days ago

    The air on earth is taking the heat from the dissipators more than blackbody radiation.

HPsquared  4 days ago

Something like a vacuum flask, I imagine. Vacuum is a very good insulator already and you minimise radiative heat transfer (infrared glow) by making a surface shiny and metallic usually (low emissivity)

  • willis936  4 days ago

    Good electrical conductors are also good thermal conductors. It's a fun system challenge to minimize what needs to be hot, but some things will have to get hot. It could be reduced to a photodiode, transistor, and a relay.

    But how do you get the power to the heater in a compact way?

    • pfdietz  4 days ago

      One notable exception to this is superconductors. One might naively think that because superconductors have zero electrical resistance, they also have zero thermal resistance. But this is wrong (sorry, Larry Niven)! The superconducting charge carriers (Cooper Pairs) have zero entropy, so they can't carry heat. Thermal conductivity of a superconducting material drops when it becomes superconductive.

      I believe high Tc superconductors have been used (or at least proposed to be used) as current leads for carrying current into low Tc superconductors from somewhat higher temperature normal conductors.